Silicon oxide selective dry etch process

ABSTRACT

Systems and methods for processing a workpiece are provided. In one example, a method includes exposing the workpiece to a first gas mixture when the workpiece is at a first temperature to conduct a doped silicate glass etch process. The first gas mixture can include hydrofluoric acid (HF) vapor. The doped silicate glass etch process at least partially removes the doped silicate glass layer at a first etch rate that is greater than a second etch rate associated with removal of the at least one second layer. The method can include heating the workpiece to a second temperature. The second temperature is greater than the first temperature. The method can include exposing the workpiece to a second gas mixture when the workpiece is at a second temperature to remove a residue from the workpiece.

PRIORITY CLAIM

The present application is based on and claims priority to U.S.application Ser. No. 16/557,346, entitled “Silicon Oxide Selective DryEtch Process,” having a filing date of Aug. 30, 2019, which isincorporated by reference herein.

FIELD

The present disclosure relates generally to processing of a workpiece,such as a semiconductor workpiece.

BACKGROUND

The processing of semiconductor workpieces can involve deposition,patterning and removal of different materials layers on a substrate toform a multilayer structure. For better patterning alignment in 3Ddevice structure fabrication, each layer is approximately planar. Ineach layer, dielectric materials such as silicate glasses can be used toseparate structures and insulate conductive materials. Doped silicateglass including borosilicate glass (BSG), phosphosilicate glass (PSG)and borophosphosilicate glass (BPSG) is commonly used as the dielectricor insulating layer between conductive materials because its meltingpoint is typically much lower than regular glass or other dielectricmaterials. A lower melting temperature allows a reflow of doped silicateglass at a relative low temperature into patterned structures beforeplanarization.

Silicate glass films can be deposited by plasma enhanced chemical vapordeposition (PECVD) system using liquid tetraethoxysilane (TEOS) as asource of silicon instead of hazardous silane gas. BSG, PSG or BPSGfilms can be deposited with addition of boron and phosphorus precursorsin PECVD processes, respectively. The boron and/or phosphorus precursorscould be organic or inorganic in nature. For instance, the boronprecursors can include B₂H₆ and TEB (triethylborate), and the phosphorusprecursors can include PH₃ and TEPO (triethylphosphate).

Certain process manufacturing flow designs call for removal of refloweddoped silicate glass inside patterned structures, including somesilicate glass liftoff processes in high capacity Dynamic Random AccessMemory (DRAM) device fabrication. It is desirable to remove dopedsilicate glass with high selectivity towards other materials, such asundoped silicate glass, silicon nitride, titanium nitride, and silicon(e.g., polysilicon). Device dimension continues to decrease, and devicestructure aspect ratio continues to increase in semiconductormanufacturing. Thus the requirements on etch selectivity are becomingmore stringent.

Wet etch processes are common in semiconductor manufacturing. However,conventional wet etch processes have some intrinsic problems and startto reach limitations in advanced semiconductor fabrications, especiallyin removing significant amount of materials inside small and high-aspectratio structures. Wet etch rate can be limited by process temperature.It can be further constrained by a slow diffusion of wet etch chemicalprecursors into and wet etch chemical reaction products out of highaspect ratio nanostructures. In addition, a complete removal of wetchemicals from high aspect ratio nanostructures after the wet etchprocess can be very challenging, as most of the wet etch chemicalprecursors and wet etch reaction products are not volatile, thus proneto leave residues inside high aspect ratio nanostructures with standardwafer rinse and spin-dry processes. An insufficient post wet-etch waferclean/dry can also result in surface corrosion and particlecontamination on wafer surfaces. Finally, narrow and high aspect rationanostructures in advanced semiconductor devices are very fragile, andsurface tension in wet etch processes can lead to significant patterndamage and sometimes pattern collapse and device failure.

Comparing with wet etch processes, vacuum based dry etch processes canbe more effective, more efficient, more versatile and more suitable formaterials removal inside high aspect ratio nanostructures. Workpiecetemperature can be more flexible in dry etch processes to optimize etchrate and selectivity and to accommodate process integrationrequirements. In addition, vacuum based dry etch processes have betterextendibility for materials removal inside high aspect rationanostructures with gas phase precursor adsorption and volatile reactionproduct desorption. Finally, as mentioned above, wet etch processes canhave issues with surface tension induced pattern collapse and post etchresidues inside high aspect ratio structures. They are in general notissues for gas phase based dry etch processes.

SUMMARY

Aspects and advantages of embodiments of the present disclosure will beset forth in part in the following description, or may be learned fromthe description, or may be learned through practice of the embodiments.One example aspect of the present disclosure is directed to a method foretching a doped silicate glass layer on a workpiece. The workpiece caninclude a doped silicate glass layer and at least one second layer. Thesecond layer can be a different material relative to the doped silicateglass layer. The method can include exposing the workpiece to a firstgas mixture when the workpiece is at a first temperature to conduct adoped silicate glass etch process. The first gas mixture can includehydrofluoric acid (HF) vapor. The doped silicate glass etch process atleast partially removes the doped silicate glass layer at a first etchrate that is greater than a second etch rate associated with removal ofthe at least one second layer. The method can include heating theworkpiece to a second temperature. The second temperature is greaterthan the first temperature. The method can include exposing theworkpiece to a second gas mixture when the workpiece is at a secondtemperature to remove a residue from the workpiece.

These and other features, aspects and advantages of various embodimentswill become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the present disclosure and, together with thedescription, serve to explain the related principles.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed discussion of embodiments directed to one of ordinary skill inthe art are set forth in the specification, which makes reference to theappended figures, in which:

FIG. 1 depicts an overview of an example process according to exampleembodiments of the present disclosure;

FIG. 2 depicts a flow diagram of an example method according to exampleembodiments of the present disclosure;

FIG. 3 depicts an example processing apparatus according to exampleembodiments of the present disclosure;

FIG. 4 depicts an example plasma processing apparatus according toexample embodiments of the present disclosure;

FIG. 5 depicts example gas injection at a separation grid according toexample embodiments of the present disclosure;

FIG. 6 depicts example heating of a workpiece according to exampleembodiments of the present disclosure;

FIGS. 7 and 8 depict example processing apparatus according to exampleembodiments of the present disclosure; and

FIG. 9 depicts example control of etch rate based on temperatureaccording to example aspects of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments, one or moreexamples of which are illustrated in the drawings. Each example isprovided by way of explanation of the embodiments, not limitation of thepresent disclosure. In fact, it will be apparent to those skilled in theart that various modifications and variations can be made to theembodiments without departing from the scope or spirit of the presentdisclosure. For instance, features illustrated or described as part ofone embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that aspects of the presentdisclosure cover such modifications and variations.

Example aspects of the present disclosure are directed to processing aworkpiece, such as a semiconductor workpiece. For instance, exampleaspects of the present disclosure are directed to processes for removalof doped silicate glass materials (e.g., BSG, PSG and BPSG) with highselectivity relative to other materials on a workpiece.

Processes according to example aspects of the present disclosure canprovide a dry etch process for removing doped silicate glass materialsselectively relative to other materials on a workpiece. For instance, anall-dry process can include exposing the workpiece to a gas mixtureincluding hydrofluoric acid (HF) vapor at a first temperature. The firsttemperature can be, for instance, in the range of about 20° C. to about200° C., such as about 50° C. To remove surface residue, the process caninclude heating the workpiece to a second temperature that is greaterthan the first temperature and continuing exposure of the workpiece tothe gas mixture including the HF vapor. The second temperature can be,for instance, about 150° C. to 400° C.

The processes according to example aspects of the present disclosure canyield a fast and clean removal of a doped silicate glass that isselective relative to other materials on a workpiece, such as undopedsilicate glass, silicon nitride, titanium nitride and silicon. Forexample, BPSG thin films can be removed at an etch rate of about 5000Å/min or greater, and there is no BPSG and etch residue afterward. Insome instances, etch selectivity of doped silicate glasses can be aboutor greater than 1000:1 relative to undoped silicate glass, siliconnitride, titanium nitride, silicon, and other materials.

Aspects of the present disclosure are discussed with reference to a“workpiece” “wafer” or semiconductor wafer for purposes of illustrationand discussion. Those of ordinary skill in the art, using thedisclosures provided herein, will understand that the example aspects ofthe present disclosure can be used in association with any semiconductorsubstrate or other suitable workpiece. In addition, the use of the term“about” in conjunction with a numerical value is intended to refer towithin ten percent (10%) of the stated numerical value. A “pedestal”refers to any structure that can be used to support a workpiece.

FIG. 1 depicts an overview of an example process 60 for removing a dopedsilicate glass (BSG, PSG, BPSG) layer according to example aspects ofthe present disclosure. The process 60 can be performed on a workpiece50 (e.g., a semiconductor wafer). A portion of the workpiece 50 isillustrated in FIG. 1. The workpiece 50 can include a first layer thatis a doped silicate glass (BSG, PSG, BPSG) layer 56 and at least onesecond layer 54. The at least one second layer 54 can be of, forinstance, undoped silicate glass, silicon nitride, titanium nitride,silicon, or other materials. The doped silicate glass (BSG, PSG, BPSG)layer 56 and the at least one second layer 54 can be disposed, forinstance, on a substrate 52 (e.g., silicon or other semiconductorsubstrate).

In some embodiments, the doped silicate glass layer 56 is borosilicateglass (BSG) having a boron concentration between about 1% and about 10%.In some embodiments, the doped silicate glass layer 56 isphosphosilicate glass (PSG) having a phosphorus concentration betweenabout 1% and about 10%. In some embodiments, the doped silicate glasslayer 56 is borophosphosilicate glass (BPSG) layer having a boronconcentration between about 1% and about 10% and having a phosphorusconcentration between about 1% and about 10%.

At 62, the process 60 can include exposing the workpiece 50 (e.g., inparticular the doped silicate glass layer 56) to a gas mixture thatincludes HF vapor to implement a doped silicate glass removal process.The gas mixture, in some embodiments, can also include a carrier gas.The carrier gas can be, for instance, nitrogen, helium, argon, xenon orother inert gas. The gas mixture does not include more than residualamounts (e.g., more than about 2% of the gas mixture) of water vapor.

The HF vapor can be exposed to the workpiece 50 when the workpiece 50 isat a first temperature. The first temperature can be in the range ofabout 20° C. to about 200° C., such as about 50° C. The HF vapor can bedelivered from an HF vapor source. In some embodiments, the HF vapor canbe generated in a remote plasma source from a first precursor containingfluorine and a second precursor containing hydrogen. The etch rate ofthe doped silicate glass layer can be controlled by adjusting the firsttemperature within the range of about 20° C. to about 200° C. (e.g.,using heating elements, heat lamps, cooling systems, etc.).

Heating the workpiece 50 to the first temperature can be accomplishedusing a heat source. In one example, the heat source can be a hot platein a direct physical contact to or in proximity to the workpiece 50. Inone example, the workpiece 50 can be in a direct physical contact to thehot plate, and the hot plate can also be used as a pedestal to supportthe workpiece 50. In another example, the workpiece 50 can be placed inproximity to the hot plate, e.g. positioned on top of a few support pinsand parallel to the hot plate. The hot plate can be heated using one ormore heating elements (e.g., electrical or fluid based heatingelements). The hot plate can be also heated by some radiative heatingsources. In yet another example, the workpiece 50 can be heated in theabsence of a hot plate directly with radiations from one or more heatinglamps (e.g., incandescent lamps, fluorescent lamps, halogen lamps, LEDlamps, gas discharge lamps, arc lamps, etc.) or radiation from otherheat sources (e.g. a remote plasma source).

As shown in FIG. 1, exposure of the workpiece to the HF vapor at 60 canleave a residue layer 58 on the workpiece 50. The residue layer 58 caninclude a boron containing substance and/or a phosphorus containingsubstance. For instance, the residue can include one or more of B₂O₃,H₃BO₃, P₂O₅, H₃PO₄, etc. The residue can also include etch byproduct,such as H₂SiF₆ and H₂O.

As shown in FIG. 1, the residue layer 58 can be removed by heating theworkpiece as shown at 64 to a second temperature and exposing theworkpiece to a gas mixture that includes HF vapor as shown at 66. Thesecond temperature can be higher than the first temperature. Forinstance, the second temperature can be about 150° C. to 400° C. Asshown in FIG. 1, this can result in the selective removal of the dopedsilicate glass layer 56 relative to the at least one second layer 54 andcan leave a clean surface with minimal or no residue.

Heating the workpiece 50 to the second temperature can be accomplishedusing a heat source. In one example, the heat source can be a hot platein a direct physical contact to or in proximity to the workpiece 50. Inone example, the workpiece 50 can be in a direct physical contact to thehot plate, and the hot plate can also be used as a pedestal to supportthe workpiece 50. In another example, the workpiece 50 can be placed inproximity to the hot plate, e.g. positioned on top of a few support pinsand parallel to the hot plate. The hot plate can be heated using one ormore heating elements (e.g., electrical or fluid based heatingelements). The hot plate can be also heated by some radiative heatingsources. In yet another example, the workpiece 50 can be heated inabsence of a hot plate directly with radiations from one or more heatinglamps (e.g., incandescent lamps, fluorescent lamps, halogen lamps, LEDlamps, gas discharge lamps, arc lamps, etc.) or radiation from otherheat sources (e.g. a remote plasma source)

In some embodiments, the doped silicate glass etch process and theresidue removal process can be integrated and performed in the sameprocessing chamber (e.g., in-situ in the same processing chamber). Insome embodiments, the doped silicate glass etch process at the firsttemperature and the residue removal process at the second temperaturecan be performed sequentially on a single pedestal inside the chamber.For instance, the workpiece can be continuously exposed to a gas mixtureincluding the HF vapor. In some other embodiments, the doped silicateglass etch process and the residue removal process can be performedsequentially on different pedestals in the same chamber, with thedifferent pedestals being operated at different temperatures. Thechamber can be designed with the separate pedestals in a carouselconfiguration.

Other implementations can be used without deviating from the scope ofthe present disclosure. For instance, in some other embodiments, thedoped silicate glass etch process and the residue removal process can beperformed in separate chambers on a cluster tool without vacuum break.In yet some other embodiments, the doped silicate glass etch process andthe residue removal process can be performed in separate chambers aspart of separate processing tools.

FIG. 2 depicts a flow diagram of an example method (200) according toexample aspects of the present disclosure. The method (200) can beperformed using a suitable processing apparatus, such as the processingapparatus(s) discussed in more detail with referenced to FIGS. 3 and 4.FIG. 2 depicts steps performed in a particular order for purposes ofillustration and discussion. Those of ordinary skill in the art, usingthe disclosures provided herein, will understand that the steps of anyof the methods provided herein can be adapted, modified, omitted,performed simultaneously, include steps not illustrated, rearranged,and/or expanded in various ways without deviating from the scope of thepresent disclosure.

At (202), the method includes placing a workpiece on a workpiece supportin a processing chamber 110. For instance, as shown in FIG. 3, themethod can include placing a workpiece 114 on a workpiece support 112 ina processing chamber 110 of a processing apparatus 100. The workpiece114 can include a doped silicate glass layer and one or more secondlayers, such as undoped silicate glass layers, silicon nitride layers,titanium nitride layers, and silicon layers, etc.

At (204) of FIG. 2, the method can include heating the workpiece to afirst temperature. The first temperature can be, for instance, in arange of about 20° C. to about 200° C., such as about 50° C. The firsttemperature can be adjusted and/or selected to obtain a desired etchrate for the doped silicate glass layer.

As an example, in the example embodiment illustrated in FIG. 3, theworkpiece 114 can be heated, for instance, using heating elements 172disposed in the workpiece support 112. The heating elements 172 can beelectric heaters, heated fluid channels, lamps, etc. In someembodiments, the workpiece 114 can be heated directly, for instance,using lamp heat sources 170. The lamp heat sources 170 can beincandescent lamps, fluorescent lamps, halogen lamps, LED lamps, gasdischarge lamps, arc lamps or other suitable radiation sourcesconfigured to heat a workpiece.

At (206), the method can include exposing the workpiece to a gas mixtureincluding an HF vapor to at least partially remove the doped silicateglass layer. The gas mixture can include HF vapor and a carrier gas. Thecarrier gas can be, for instance, an inert gas, such as helium, argon,neon, and/or nitrogen gas.

For instance, as shown in FIG. 3, the apparatus can include a gas flowsystem that includes, for instance, a gas supply 150 and gas exhaust 152configured to flow a gas mixture 155 including HF vapor through theprocessing chamber 110 containing the workpiece 114. In this way, theapparatus can expose the workpiece 114 to the gas mixture 155 includingHF vapor for at least partial removal of the doped silicate glass layer.

At (208) of FIG. 2, the method can include heating the workpiece to asecond temperature. The second temperature can be greater than the firsttemperature. For instance, the second temperature can be, for instance,150° C. to 400° C.

As an example, referring to the example embodiment illustrated in FIG.3, the workpiece 114 can be heated to the second temperature, forinstance, using heating elements 172 disposed in the workpiece support112. The heating elements 172 can be electric heaters, heated fluidchannels, lamps, etc. In some embodiments, the workpiece 114 can beheated to the second temperature, for instance, using lamp heat sources170. The lamp heat sources 170 can be incandescent lamps, fluorescentlamps, halogen lamps, LED lamps, gas discharge lamps, arc lamps or othersuitable radiation sources configured to heat a workpiece.

At (210) of FIG. 2, the method can include exposing the workpiece to agas mixture including HF vapor at the second temperature to removeresidue on the workpiece. The residue can include a boron containingsubstance and/or a phosphorus containing substance. For instance, theresidue can include one or more of B₂O₃, H₃BO₃, P₂O₅, H₃PO₄, etc. Theresidue can also include etch byproduct, such as H₂SiF₆ and H₂O.

In some embodiments, the gas mixture can be the same gas mixture exposedto the workpiece at (206). For instance, there can be a continuousexposure of the gas mixture to the workpiece while the workpiece isheated from the first temperature to the second temperature to removethe residue on the workpiece.

As an example, in the embodiment illustrated in FIG. 3, the gas flowsystem of the apparatus 100 can continuous flow the gas mixture 155 intothe processing chamber 110 for exposure to the workpiece 114 while theworkpiece 114 is heated from the first temperature to the secondtemperature and while the workpiece 114 is maintained at the secondtemperature for the residue removal process.

Referring back to FIG. 2, the method can include at (212) removing theworkpiece from the processing chamber. For instance, the workpiece 114can be removed from the processing chamber 110 of the apparatus 100. Inthis way, both the doped silicate glass etch process and the residueremoval process can be performed in-situ in the same processing chamber.

The methods according to example embodiments of the present disclosurecan be implemented using other types of processing apparatus withoutdeviating from the scope of the present disclosure. For instance, themethod can be performed using a plasma processing apparatus thatincludes a remote plasma source for generating radicals and otherspecies for processing a workpiece.

FIG. 4 depicts an example plasma processing apparatus 400 the can beused to implement the methods according to example embodiments of thepresent disclosure. As illustrated, plasma processing apparatus 400 caninclude a processing chamber 410 and a plasma chamber 420 that isseparate from the processing chamber 410. Processing chamber 410includes a workpiece support 412 operable to hold a workpiece 414 to beprocessed, such as a semiconductor wafer. In this example illustration,a plasma is generated in plasma chamber 420 (i.e., plasma generationregion) by an inductively coupled plasma source 435 and desired speciesare channeled from the plasma chamber 420 to the surface of workpiece414 through a separation grid assembly 500.

Aspects of the present disclosure are discussed with reference to aninductively coupled plasma source for purposes of illustration anddiscussion. Those of ordinary skill in the art, using the disclosuresprovided herein, will understand that any plasma source (e.g.,inductively coupled plasma source, capacitively coupled plasma source,etc.) can be used without deviating from the scope of the presentdisclosure.

The plasma chamber 420 includes a dielectric side wall 422 and a ceiling424. The dielectric side wall 422, ceiling 424, and separation grid 500define a plasma chamber interior 425. Dielectric side wall 422 can beformed from a dielectric material, such as quartz and/or alumina. Theinductively coupled plasma source 435 can include an induction coil 430disposed adjacent the dielectric side wall 422 about the plasma chamber420. The induction coil 430 is coupled to an RF power generator 434through a suitable matching network 432. Process gases (e.g., reactantand carrier gases) can be provided to the chamber interior from gassupply 450 and annular gas distribution channel 451 or other suitablegas introduction mechanism. When the induction coil 430 is energizedwith RF power from the RF power generator 434, a plasma can be generatedin the plasma chamber 420. In a particular embodiment, the plasmaprocessing apparatus 400 can include an optional grounded Faraday shield428 to reduce capacitive coupling of the induction coil 430 to theplasma.

As shown in FIG. 4, a separation grid 500 separates the plasma chamber420 from the processing chamber 410. The separation grid 500 can be usedto perform ion and electron filtering from a mixture generated by plasmain the plasma chamber 420 to generate a filtered mixture. The filteredmixture can be exposed to the workpiece 414 in the processing chamber.

In some embodiments, the separation grid 500 can be a multi-plateseparation grid. For instance, the separation grid 500 can include afirst grid plate 510 and a second grid plate 520 that are spaced apartin parallel relationship to one another. The first grid plate 510 andthe second grid plate 520 can be separated by a distance.

The first grid plate 510 can have a first grid pattern having aplurality of holes. The second grid plate 520 can have a second gridpattern having a plurality of holes. The first grid pattern can be thesame as or different from the second grid pattern. Charged particles canrecombine on the walls in their path through the holes of each gridplate 510, 520 in the separation grid. Neutral particles (e.g.,radicals) can flow relatively freely through the holes in the first gridplate 510 and the second grid plate 520. The size of the holes andthickness of each grid plate 510 and 520 can affect transparency forboth charged and neutral particles.

In some embodiments, the first grid plate 510 can be made of metal(e.g., aluminum) or other electrically conductive material and/or thesecond grid plate 520 can be made from either an electrically conductivematerial or dielectric material (e.g., quartz, ceramic, etc.). In someembodiments, the first grid plate 510 and/or the second grid plate 520can be made of other materials, such as silicon or silicon carbide. Inthe event a grid plate is made of metal or other electrically conductivematerial, the grid plate can be grounded.

In some embodiments, the method (200) of FIG. 2 can be implemented usingthe plasma processing apparatus 400 of FIG. 4. For example, at (202) theworkpiece 414 can be placed on the workpiece support 412 in theprocessing chamber. The workpiece 414 can include a doped silicate glasslayer and one or more second layers, such as undoped silicate glasslayers, silicon nitride layers, silicon nitride layers, and siliconlayers etc.

At (204), the workpiece can be heated to a first temperature. The firsttemperature can be, for instance, in a range of about 20° C. to about200° C., such as about 50° C. The first temperature can be adjustedand/or selected to obtain a desired etch rate for the doped silicateglass layer. The workpiece 414 can be heated, for instance, usingheating elements disposed in the workpiece support 412. The heatingelements can be electric heaters, heated fluid channels, lamps, etc. Insome embodiments, as discussed in more detail with respect to FIG. 6,the workpiece 414 can be heated to the first temperature by generating aplasma in the remote plasma chamber 420. The workpiece 414 can be heatedto the first temperature by maintaining the workpiece a sufficientvertical location relative to the plasma chamber 420.

At (206), the method can include exposing the workpiece to a gas mixtureincluding an HF vapor to implement a doped silicate glass etch process.As shown in FIG. 4, in some implementations, the apparatus can include agas flow system that can introduce the gas mixture 155 including HFvapor into the plasma chamber 420. There may be no plasma generated inthe plasma chamber 420. The gas mixture 155 would continue through theseparation grid 500 (acting as a showerhead) into the processing chamber410 for exposure to the workpiece 414.

The gas mixture 155 including the HF vapor can be introduced into theprocessing chamber 410 in other ways without deviating from the scope ofthe present disclosure. For instance, the gas mixture can be introducedinto the processing chamber 410 at or below the separation grid.

FIG. 5 depicts example injection of a gas mixture 155 including HF vaporat a separation grid 500 according to example embodiments of the presentdisclosure. More particularly, the separation grid 500 includes a firstgrid plate 510 and a second grid plate 520 disposed in parallelrelationship for ion/electron/UV filtering.

The first grid plate 510 and a second grid plate 520 can be in parallelrelationship with one another. The first grid plate 510 can have a firstgrid pattern having a plurality of holes. The second grid plate 520 canhave a second grid pattern having a plurality of holes. The first gridpattern can be the same as or different from the second grid pattern.Subsequent to the second grid plate 520, a gas injection source 230 canbe configured to admit a gas mixture 155 including HF vapor into theseparation grid. The gas mixture 155 including HF vapor can pass througha third grid plate 535 for exposure to the workpiece.

The grid assembly 500 can be independently heated by heating elements(not shown). The heating elements can be electric heaters, heated fluidchannels, etc.

The present example is discussed with reference to a separation gridwith three grid plates for example purposes. Those of ordinary skill inthe art, using the disclosures provided herein, will understand thatmore or fewer grid plates can be used without deviating from the scopeof the present disclosure. In addition, the gas injection source 230 canbe located at other locations relative to the separation grid 500, suchas between the first grid plate 510 and the second grid plate 520, belowthe third grid plate 535, or below the entire separation grid 500. Thegas injection source 230 can inject gas at any angle with respect to theseparation grid 600.

In some embodiments, the HF vapor can be generated by inducing a plasmain the plasma chamber interior 425 using the plasma source 435 andproviding species generated in the plasma through the separation grid500 for exposure to the workpiece 414. For instance, inductive plasmasource 435 can generate plasma in a process gas mixture having Fcontaining precursors (e.g., F₂, CF₄, NF₃, CF_(x)H_(y), etc.) and Hcontaining precursors (e.g., H₂, CH₄, C₂H₆, C_(x)H_(y), etc.). Speciesgenerated in the plasma can pass through the separation grid 500 forexposure to the workpiece.

At (208) the method can include heating the workpiece 414 to a secondtemperature. The second temperature can be greater than the firsttemperature. For instance, the second temperature can be, for instance,150° C. to 400° C. The workpiece 414 can be heated to the secondtemperature, for instance, using heating elements disposed in theworkpiece support 412. The heating elements can be electric heaters,heated fluid channels, lamps, etc. In some embodiments, the workpiece414 can be heated to the second temperature, for instance, using lampheat sources (not shown). The lamp heat sources can include incandescentlamps, fluorescent lamps, halogen lamps, LED lamps, gas discharge lamps,arc lamps, etc.

In some embodiments, as shown in FIG. 6, the workpiece 414 can be heatedto the second temperature by adjusting the vertical location of theworkpiece 414 to a different vertical location relative to the plasmachamber 420 (e.g. with lift pins 415). For instance, as shown in FIG. 6,the lift pins 415 can maintain the workpiece 414 at a first verticallocation from the plasma chamber 420 to expose the workpiece to the gasmixture including HF vapor at the first temperature for the dopedsilicate glass etch process. The lift pins 415 can lift the workpiece414 to a second vertical location from the plasma chamber 420 that iscloser to the plasma chamber 420 relative to the first vertical locationto expose the workpiece to the HF vapor at the second temperature forthe residue removal process.

At (210) of FIG. 2, the method can include exposing the workpiece to agas mixture including HF vapor at the second temperature to removeresidue on the workpiece. The residue can include a boron containingsubstance and/or a phosphorus containing substance. For instance, theresidue can include one or more of B₂O₃, H₃BO₃, P₂O₅, H₃PO₄, etc. Theresidue can also include one or more etch byproducts, such as H₂SiF₆ andH₂O.

In some embodiments, the gas mixture can be the same gas mixture exposedto the workpiece at (206). For instance, there can be a continuousexposure of the gas mixture to the workpiece while the workpiece isheated from the first temperature to the second temperature to removethe residue. As an example, in the embodiment illustrated in FIG. 4, thegas flow system of the apparatus 400 can deliver a continuous flow ofthe gas mixture 155 into the processing chamber or a continuous flow ofradicals generated in a plasma for exposure to the workpiece 414.

The method can include at (212) removing the workpiece from theprocessing chamber. For instance, the workpiece 414 can be removed fromthe processing chamber 410 of the apparatus 400. In this way, both thedoped silicate glass etch process and the residue removal process can beperformed in-situ in the same processing chamber.

In example embodiments, the silicate glass removal process according toexample embodiments of the present disclosure can be implemented suchthat the silicate glass etch process is performed when heating theworkpiece to the first temperature on a pedestal in a processing chamberand the residue remove process is performed when heating the workpieceto the second temperature using a different pedestal in the sameprocessing chamber. For instance, FIG. 7 depicts a plane view of aprocessing chamber 610 of an apparatus 600 having a first pedestal 612and a second pedestal 614. The first pedestal 612 and the secondpedestal 614 may be part of the same integral structure 616 or may bephysically separated. The silicate glass etch process can be implementedby heating the workpiece to the first temperature at the first pedestal612. The workpiece can be transferred to the second pedestal 614 wherethe residue removal process can be implemented by heating the workpieceto the second temperature that is greater than the first temperature.The workpiece can be exposed to a gas mixture including HF vapor at boththe first pedestal 612 and the second pedestal 614.

In some embodiments, the silicate glass removal process according toexample embodiments can be performed with the workpiece at differentprocessing stations in an apparatus having a carousel configuration. Forinstance, FIG. 8 depicts one example processing apparatus 700 having acarousel configuration. The apparatus 700 can rotate a workpiece amongdifferent processing stations, 712, 714, 716, and 718 in a processingchamber 710. The silicate glass etch process can be implemented byheating the workpiece to the first temperature at the first processingstation 712. The workpiece can be rotated to the second processingstation 714 where the residue removal process can be implemented byheating the workpiece to the second temperature that is greater than thefirst temperature. The workpiece can be exposed to a gas mixtureincluding HF vapor at both the first processing station 712 and thesecond pedestal 714. Different workpiece processing steps can optionallybe performed at processing stations 716 and 718.

In some embodiments, the silicate glass removal process according toexample aspects of the present disclosure can be implemented indifferent process chambers. For instance, the silicate glass removalprocess can be implemented such that the silicate glass etch process isperformed by heating the workpiece to the first temperature in a firstprocess chamber and the residue removal process is performed by heatingthe workpiece to the second temperature in a different process chamber(e.g., a second process chamber as part of a cluster tool).

FIG. 9 depicts example etch rate of the doped silicate glass layer as afunction of workpiece temperature during a doped silicate glass etchprocess according to example aspects of the present disclosure. As shownby curve 800, high etch rates of doped silicate glass can be achieved byexposing the workpiece to a gas mixture including HF vapor attemperatures in the range of greater than or equal to about 100° C. Thetemperature can be adjusted to achieve a desired etch rate for the dopedsilicate glass layer.

Example process parameters for an example doped silicate glass etchprocess are provided below:

-   -   Gas Mixture: HF Vapor+Carrier Gas    -   HF Partial Pressure: 10 mTorr to 10 Torr    -   Total Gas Flow Rate: 100 sccm-20 slm    -   First Temperature: 20° C. to 200° C.    -   Second Temperature is higher than First Temperature and    -   Second Temperature: 150-300° C.

Example selectively results for a doped silicate glass etch processrelative to other layers on a workpiece obtained using the processparameters set forth in the example above are shown in Table 1 below.

Etch Amount Selectivity Material (Angstroms) BPSG to layer BPSG >4500n/a Thermal oxide <1 >4500 TEOS Oxide <4 >1,000 TiN <4 >1,000 LPCVDNitride 2 >2,000 PECVD Nitride <5 ~1,000 Poly silicon <1.5 >3,000

While the present subject matter has been described in detail withrespect to specific example embodiments thereof, it will be appreciatedthat those skilled in the art, upon attaining an understanding of theforegoing may readily produce alterations to, variations of, andequivalents to such embodiments. Accordingly, the scope of the presentdisclosure is by way of example rather than by way of limitation, andthe subject disclosure does not preclude inclusion of suchmodifications, variations and/or additions to the present subject matteras would be readily apparent to one of ordinary skill in the art.

What is claimed is:
 1. A method for etching a doped silicate glass layeron a workpiece, wherein the workpiece comprises the doped silicate glasslayer and at least one second layer, the second layer being a differentmaterial than the doped silicate glass layer, and the method comprising:placing the workpiece on a workpiece support in a processing chamber;generating a mixture from a plasma in a remote plasma chamber from aprocess gas comprising hydrogen containing precursors and fluorinecontaining precursors; exposing the workpiece to the mixture when theworkpiece is at a first temperature; increasing a temperature of theworkpiece to a second temperature by heating the workpiece using a heatsource; exposing the workpiece to the mixture generated from the plasmain the remote plasma chamber during increasing of the workpiece to thesecond temperature; exposing the workpiece to the mixture generated inthe remote plasma chamber when the workpiece is at the secondtemperature; removing the workpiece from the processing chamber.
 2. Themethod of claim 1, wherein the doped silicate glass is borosilicateglass, and boron concentration is between about 1% and about 10%.
 3. Themethod of claim 1, wherein the doped silicate glass is phosphosilicateglass, and phosphorus concentration is between about 1% and about 10%.4. The method of claim 1, wherein the doped silicate glass isborophosphosilicate glass, boron concentration is between about 1% andabout 10%, and phosphorus concentration is between about 1% and about10%.
 5. The method of claim 1, wherein the first temperature is in arange of about 20° C. to about 200° C.
 6. The method of claim 1, whereinthe first temperature is about 30° C. to about 90° C.
 7. The method ofclaim 1, wherein the second temperature is about 150° C. to about 400°C.
 8. The method of claim 1, wherein the second temperature is about150° C. to about 250° C.
 9. The method of claim 1, wherein the at leastone second layer is titanium nitride.
 10. The method of claim 1, whereinthe at least one second layer is silicon nitride.
 11. The method ofclaim 1, wherein the at least one second layer is silicon.
 12. Themethod of claim 1, wherein the at least one second layer is undopedsilicate glass.
 13. The method of claim 1, wherein exposing theworkpiece to the mixture when the workpiece is at a first temperatureoccurs when the workpiece is at a first vertical position.
 14. Themethod of claim 13, wherein exposing the workpiece to the mixture whenthe workpiece is at the second temperature occurs at a second verticalposition.
 15. The method of claim 1, wherein the second verticalposition is closer to a separation grid separating the processingchamber from the remote plasma chamber.
 16. The method of claim 1,wherein the plasma is generated using an inductively coupled plasmasource.
 17. The method of claim 1, wherein the heat source comprises oneor more heating elements located in the workpiece support.
 18. Themethod of claim 1, wherein the heat source comprises one or more lamps.19. The method of claim 1, wherein the heat source comprises the remoteplasma chamber.
 20. A method for etching a doped silicate glass layer ona workpiece, wherein the workpiece comprises a doped silicate glasslayer and at least one second layer, the second layer being a differentmaterial than the doped silicate glass layer, and the method comprising:placing the workpiece on a workpiece support in a processing chamber;generating a mixture from a plasma in a remote plasma chamber from aprocess gas comprising hydrogen containing precursors and fluorinecontaining precursors; exposing the workpiece to the mixture when theworkpiece is at a first vertical position relative to the remote plasmachamber; exposing the workpiece to the mixture generated in the remoteplasma chamber when the workpiece is at a second vertical positionrelative to the remote plasma chamber; removing the workpiece from theprocessing chamber.